One known apparatus for deriving an indication of a point source emitter of optical energy in a relatively large field of view involves an array of linearly arranged point source detectors. Each of the point source detectors has a width approximately equal to the width of a point source target, as projected by an optical system onto an image plane. In response to optical energy irradiating the point source detector, the detector generates a current that is supplied to a data processing network. To minimize the number of detectors in the array, the detectors have slightly displaced narrow fields of view that are scanned so that the field of view of each detector traces a relatively narrow, substantially straight line path across the large field of view. The paths traced by adjacent detectors are substantially parallel to each other, whereby a series of straight lines is traced by the entire array across the field of view.
In response to a point source irradiating one of the detectors, that detector derives a pulse type output which is coupled via a preamplifier to a signal processing network that is capable of recognizing whether the pulse is in response to a point source emitter. The prior art, in addition to requiring a separate preamplifier for each detector, may erroneously recognize relatively large, non-point source emitters, such as clouds, as point source emitters. While data handling circuits have been designed to distinguish point source from non-point source emitters, these circuits have a tendency to be relatively complex and have not, in all cases, been able to distinguish point source from non-point source emitters.
It is, accordingly, an object of the present invention to provide a new and improved apparatus for enabling point source emitters of optical energy to be detected in a relatively large field of view with an array of point source detectors that is scanned across the field of view.
An additional object of the invention is to provide a new and improved apparatus for detecting a point source emitter in a relatively large field of view with an array of point source detectors that is scanned across the field of view and wherein non-point source emitters have substantially no effect on an output signal derived from preamplifiers connected to the array.
Another object of the invention is to provide an apparatus for indicating the presence of a point source emitter of optical energy in a relatively large field of view wherein the field of view is scanned by an array of point source detectors and there is a substantial reduction in the number of preamplifiers connected to the detectors.